This invention relates to a magnetic cassette tape reproduction and/or recording system and, more particularly, to such a system in which dual tape transports and associated head assemblies are provided on the same chassis.
The advent of the magnetic tape cassette, in which a supply of tape along with a supply hub and a tape-up hub are disposed in a self-contained housing, has revolutionized the home market for tape recording equipment largely since the cassette is extremely convenient to use and yet provides reasonably good sound quality.
When the tape cassette and its associated reproducing and/or recording apparatus, hereinafter referred to as "deck", was originally introduced, there was a significant gap in sound quality between it and the traditional open-reel tape decks. However, this gap has been narrowed considerably with the introduction of improved tape transports, improved noise reduction systems, metal alloy tape, and electronic techniques to provide frequency dependent equalization, adequate overload margins in the recording stage and proper matching of the signal current from the record amplifier to the record head. However, the one area in which the open-reel deck still holds a significant advantage over the cassette deck is in the length of play/recording time. For example, many popular open-reel decks utilize ten and one-half inch reels and a tape speed of three and three-quarter inches per second which provides the user with three hours of uninterrupted program material. However, when operating an audio cassette deck at the standard speed of one and seven-eighths inches per second with the most popular "C-90" cassette, the user is provided with only forty-five minutes of uninterrupted program material.
Attempts have been made to alleviate this major problem by providing the tapes with additional lengths which permit uninterrupted play for sixty minutes and even ninety minutes, and/or reducing the speed to fifteen-sixteenths inches per second. However, both of these techniques result in much less than optimum performance from a sound quality standpoint, since they introduce severe compromises in the recording and playback processes.
One other solution to extend the playing time of an audio cassette deck has been to provide an "automatic reverse" feature in which the tape travels in one direction for its complete length and then automatically reverses so that it travels in the other direction. Although this has proved to be a satisfactory compromise for non-critical applications, it still has practical time limitations since the C-90 cassette would be limited to a ninety minute program. In addition, the reversing technique requires movement of the tape heads to another section of the tape which requires expensive hardware. Also, in these arrangements, it is extremely difficult to maintain a critical alignment of the tape heads, which is essential to avoid the possibility of compromising the sound quality.